[XeTeX] Roman Numerals as stylistic alternatives

[enrico.gregorio at univr.it]

> enrico.gregorio at univr.it wrote:
> 
> > When you highlight characters in a PDF and copy them you get the codes and
> > all that it's attached to them. The problem with Roman numerals is that a
> > "digit" has different meanings depending on the context. The "C" in "CXV"
> > means 1, but in "CMXV" it means nothing by itself.
> 
> I'm not entirely convinced that I agree.  I would argue that the "C"
> of "CXV" means "100", not "1"; in "CMXV" it means "subtract 100".
> At least, that's what we were taught at school !

/We/ know that the "C" in "CXV" means "add 100", because we see the whole
number. That "C" should be translated into a 1. But not when the "C" comes
before an "M". And when we find "CC" we have to translate it into a 2. With the
problems of the zeros in between, like in "CCII". If we store the number "CXV"
as three glyphs, the information is lost when only one glyph is examined (for
copying and pasting, for example).

What the OP wants is that "CXV" is stored as a unique glyph representing 115.
Maybe this can be done by reserving, say, five thousand slots in Unicode to
contain the numbers from 1 to 5000 in Roman form that are built from the basic
digits, embedding in the font (or in the typesetting engine) the algorithm for building
them from the Western/Arabic representation. This might be done in two passes:
represent the number using the codes for Roman numerals and start a ligaturing
process.

Actually, Roman numerals are mostly used when the numerical information is
almost irrelevant as such. Nobody uses the "XIV" in "Louis XIV" to perform
calculations. That's just a different way of writing "quatorze". 

I see it just as the ability to copy "quatorze" from a text and paste it into a
worksheet cell accepting numbers to get 14. In the case of Roman numerals
it may be simpler, of course. But is it useful?

Ciao
Enrico

--
Enrico Gregorio          + Dipartimento di Informatica          + Tel: +39 045 8027937
Enrico.Gregorio at univr.it + Università degli Studi di Verona     +
(gregorio at math.unipd.it) + Strada le Grazie 15 / I-37134 Verona + Fax: +39 045 8027928